In the coming year, we propose to continue producing antiserum in rabbits to the remaining 51 "untypable" isolates. If the rate of 5 isolates per "new" antiserum produced continues, this could encompass ten more serotypes distinct from RV types 1A, 1B and 2 through 89. Studies on variation in antigenic characterization of field strains, particularly those types which show antigenic relatedness to one or more RV serotypes: e.g. RV9/32/67. Experiments to study the effect of propagating these viruses in the presence of homologous and heterologous (related) antisera will be conducted. Further evidence of dual infection with two rhinovirus serotypes will be sought, and cells will be infected with various combinations of two rhinoviruses to attempt to determine the effect of dual infection in an experimental situation. Antibody titrations on rhinovirus shedders and family contacts are nearly completed. The analysis of these data will be a major part of the work for coming year.